NEW YORK – The off-color jokes flew around the room. As the anecdotes got bawdier, the laughter intensified. Some recited from memory, others read from notebooks they brought along.

The setting for the hilarity was the Montefiore Einstein Cancer Center at Montefiore Hospital. The participants were cancer patients, some with advanced stages of the illness.

They were taking part in the hospital's monthly "Strength Through Laughter" therapy. It is one of several types of laughter or humor therapy being offered by medical facilities around the country for patients diagnosed with cancer or other chronic diseases.

While the verdict is out on whether laughter plays a role in healing, the American Cancer Society and other medical experts say it reduces stress and promotes relaxation by lowering blood pressure, improves breathing and increases muscle function.

On a recent day before Halloween, many of the two dozen patients at Montefiore arrived in costume to "spook cancer."

"The session makes you feel better," said Luz Rodriguez, 57, a breast cancer patient now in remission, who came disguised as a security officer. "I feel healthy when I laugh."

The laughs generated a warmth among the group that was palpable, particularly when Rodriguez changed into an angel costume and went around offering a red rose and a hug or kiss to each of the participants.

Their facilitator, senior oncology social worker Gloria Nelson, started the session five years ago to help cancer patients focus on living, instead of dying.

"They have such amazing strength, but it's a constant challenge, the fear of it coming back, how to go on living knowing you have cancer," said Nelson, who came dressed as the mother of the bride. "Every time they laugh, it's like kicking cancer out the door. You're taking control, you're saying it's not controlling me."

The most famous case of laughter's therapeutic effects on the body was described by Norman Cousins, editor of the Saturday Review, in his 1979 book, "Anatomy of an Illness." He claimed that a combination of laughter and vitamins cured him of a potentially fatal illness.

"I made the joyous discovery that 10 minutes of genuine belly laughter had an anesthetic effect," he wrote.

Still, laughter therapy is not for everyone. Some cancer patients are so overwhelmed with their diagnosis that they are unable to participate. Medical experts stress that laughter and other complementary therapies like acupuncture, massage and meditation are not substitutes for traditional medical treatment but can be used to help relieve the anxiety brought on by the disease.

At the Cancer Treatment Centers of America in Zion, Ill., patients experience another form of laughter therapy that bypasses jokes. In this version, patients practice laughter sounds like "he-he," "ha-ha," and "ho-ho," greet each other with laughter instead of words and engage in games like a pretend snowball fight until laughter overtakes them.

The staff at the center first tried it in 2004. They felt "weird and silly" but when they tried it out with patients the next day, the laughter soon because contagious, said Katherine Puckett, a licensed clinical social worker and a mind-body medicine expert.

The therapy has since been integrated into the culture of the hospital, and is also offered at the center's facilities in Philadelphia, Tulsa and Seattle.

Steve Wilson, a psychologist who runs the World Laughter Tour, which also trains and certifies laughter club leaders, said about two dozen hospitals around the country have asked to be trained in the method in the past two to three years. One hospital wants to try the therapy with lung transplant patients because laughter allows more oxygen to move through the body.

An international program with a similar goal but totally different approach is "Caring Clowns." The Thomas Jefferson University Hospital in Philadelphia uses the program of costumed volunteers to get patients to giggle — or at least smile — and open up.

"One of the challenges of being diagnosed with cancer is preserving your dignity ... when we tell you to put on a gown where the back half is missing and everyone's examining you and asking about bodily functions," said Dr. Richard Wender, former president of the American Cancer Society and the hospital's chief of family medicine.

The clown volunteers, he said, create a sense of comfort that helps narrow the "interpersonal gap" between patient and medical staff.

Robbie Robinson, 52, a non-Hodgkin's Lymphoma survivor, became a certified laughter leader after witnessing the "coping mechanism" laughter offered him as a patient at CTCA.

"Some people came in wheelchairs, some were helped by family and friends. You could tell people were down ... then I noticed that through some stimulated laughter, people started smiling. They forgot their troubles. You could see the pressure come off them."

The nonprofit Rx Laughter, meanwhile, focuses on managing patient pain and improving mental health through comic entertainment, including films and TV clips. It is a unique collaboration between the entertainment and medical fields that was founded in 1998 by Sherry Dunay Hilber, one-time director of prime time programming for ABC and CBS.

Rx Laughter's participation in two large medical studies discovered that patients who watched funny videos during certain painful procedures were more relaxed and tolerated the pain longer. It also found that cancer patients had less pain and slept better after such entertainment. The organization offers a variety of programs for hospitals, nursing homes, cancer support groups and rehabilitation clinics.

"Comic entertainment is at our fingertips 24/7. ... Watching our favorite shows and films can get us through very stressful times — all the more important in light of the cost of psychotherapy that many people cannot afford, and the problematic side effects of too many pain killers," said Hilber.